XPenguins animates a friendly family of penguins in your root window.
They drop in from the top of the screen, walk along the tops of your
windows, up the side of your windows, levitate, skateboard, and do
other similarly exciting things. XPenguins is now themeable so if
you're bored of penguins, try something else. The themes that come
with this package are "Penguins", "Classic Penguins" and "Turtles".